The International Atomic Energy Agency has begun its first survey since the release of treated and diluted water from the Fukushima Daiichi nuclear power plant into the ocean started earlier this year.

The IAEA delegation met at the Foreign Ministry in Tokyo on Tuesday with officials of the industry ministry, the plant operator Tokyo Electric Power Company, and other people in charge.

IAEA Deputy Director General Lydie Evrard said the IAEA's mission will continue until the release of the water is finished. She said the IAEA will continue its safety review with objectivity, based on the science and with an independent approach. She said the IAEA will share the outcome of the safety review with the international community to build confidence in Japan and beyond.

The UN nuclear watchdog's team, consisting of experts from 11 countries including Britain, South Korea and China, is expected to stay in Japan until Friday. China opposes the release of the treated and diluted water.

The team members are scheduled to inspect the plant, observe how the treated and diluted water has been released and confirm the results of the monitoring study. The IAEA is planning to disclose a report in about two months.

The treated and diluted water has been released from the plant on two occasions, one starting in August, the other in October.

Water accumulated at the plant is treated to remove most radioactive substances, but still contains tritium.

Before the treated water is released into the sea, it is diluted to reduce tritium to about one-seventh of the guidance level set by the World Health Organization for drinking water.